Multiple antibiotic resistance index (MARI) is used to determine the multiple antibiotic resistance nature of particular pathogenic bacteria to an array of antibiotics or antimicrobial agents to which the test organism have been previously tested for. MARI helps researchers to know whether or not a particular pathogenic bacterium is multidrug resistant or not. It is calculated using a simple mathematical formular. When calculating MARI, it should only be determined for those bacterial isolates or pathogenic bacteria that showed multiple antibiotic resistances to the different classes of antibiotics used in the general antimicrobial susceptibility testing (AST). The multiple antibiotic resistance index (MARI) of selected multidrug resistant isolates can be calculated using the following formular:
MARI = A/B
A = number of antibiotics to which the resistant bacteria was resistant to.
B = total number of antibiotics to which the resistant bacteria has been evaluated for.
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